package WrittenTest;

import java.util.Scanner;

public class test20 {
    // 青蛙跳台阶问题, 可转化为斐波那契数列求解
    // 算法原理: 递归
    public static int Fib(int n) {
        if (n == 1) {
            return 1;
        }
        if (n == 0) {
            return 1;
        }
        return Fib(n - 1) + Fib(n - 2);
    }

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int tmp = Fib(n);
        System.out.println(tmp);
    }
}
